9317020 Morison The proposed work is part of an integrated research program ("Anzflux") into the oceanographic structure of upper mixed layer of the eastern Weddell Sea. It is to be carried out from the RVIB Nathaniel B. Palmer in the austral winter of 1994. The work proposed here is to make high resolution measurements of the horizontal variability of temperature and salinity to help determine the three-dimensional structure of coherent convection features. The measurements will be made with instruments on a remotely operated free-ranging underwater vehicle (the Autonomous Conductivity Temperature Vehicle -- ACTV). The postulated high oceanic heat flux values in the eastern Weddell Sea require the existence of a mechanism that enhances the vertical heat flux. Possible such mechanisms are coherent roll instabilities in the mixed layer, convection under leads and other openings in the ice, or internal waves. Single point measurements can only suggest the existence of these mechanisms; the identification of the particular mechanism requires information on their horizontal variability. The ACTV, which is 160 centimeters long and 9 centimeters in diameter, is capable of one hour of operation at a speed of two meters per second. It can be programmed to dead reckoned course as far as 1.5 kilometers from a homing beacon, and can cover about five kilometers per run. It carries commercially available thermometers and conductivity sensors whose precision is better than one thousandths of a degree and one part in thirty thousand salinity units. The vehicle will be operated from a small, light- weight hut set up on the sea ice, and will be deployed and recovered through a one meter diameter hole. ***
